Grind all chutney ingredients with 1/4 cup water and make a fine paste. Keep it aside.
Heat oil in a pan in a medium heat, add mustard seeds, chana dal, urad dal, wait till it crackles. Add whole red chili and curry leaves, fry it until brown.
Pour over the tempering on coconut chutney. Chutney is ready to serve with dosa or idli.